How to make table borders invisible with CSS

It's possible that what you're describing is cellspacing. If that's the case try this in your HTML:

<table cellpadding="0" cellspacing="0" border="0">
  ...
</table>

Cellspacing refers to the space between cells; it's not a border exactly. So, if you're seeing invisible or non-colored spaces between your tds, try adding the cellspacing="0" attribute to your table tag.

You can also use this style:

#table1 {border:0px solid transparent;} 

Try this

#table1 {
   border-collapse: collapse;
}